In recent years, home servers have been prevalent. A home server is a device for accumulating and distributing various contents (e.g., movies and music) by communicating, via a home network, with a recording/playback device, a digital camera that is connected to the home server as needed, or the like. Since the contents may include personal information, a security function is necessary that protects contents in case that a home server is stolen.
Conventionally, authentication is used as a means of ensuring security for contents protection. However, it is bothersome for a user to perform authentication for each use even though the home server is used at home where security is ensured.
Accordingly, a technique for ensuring security without relying on authentication is demanded for a home server, etc. As such a technique, the following is commonly known as prior art.
A device disclosed in Patent Literature 1 is based on the premise that the device is always connected to a network. When physically disconnected from the network, the device sets off an alarm, thereby preventing theft. However, according to this technique, although the alarm is set off, if the device is actually stolen, contents cannot be protected.
In this regard, Patent Literature 2 discloses a device designed in consideration of such theft. The device disclosed in Patent Literature 2 acquires positional information by receiving radio waves from a base station, judges whether contents are used at a legitimate position, and performs access restriction depending on a result of the judgment. The device enables access to the contents when the positional information indicates a predetermined place. Also, in case of theft or the like, the device disables access to the contents since the positional information, which is acquired by receiving radio waves from the base station, does not indicate the predetermined place.